For people with radiographic knee osteoarthritis (KOA), more severe structural disease in the knee and decreased physical performance were associated with a higher risk of depressive symptoms according to a study presented on June 14, 2018, at the 2018 Annual European Congress of Rheumatology (EULAR) in Amsterdam.

“Study findings suggest that cumulatively, over time, the strongest risk factor for the onset of depression is worsening structural disease severity, rather than increasing pain and functional disability,” says Rathbun. This is an important distinction for physicians treating knee osteoarthritis (OA) , because although structural disease progression may be difficult to determine in a routine doctor’s visit, it may come before increases in pain and functional disability, and ultimately, lead to deteriorations in psychosocial health, says Rathbun.

Osteoarthritis, and Knee OA, Are Common Causes of Chronic Pain

Osteoarthritis is the most common joint disorder, affecting more than 10 percent of men and 13 percent of women over the age of 60. The most common symptoms are joint pain and stiffness according to the Arthritis Foundation. In knee OA, the cartilage begins to break down and there is a failure of normal joint repair, says Rathbun. People with knee OA can have trouble walking, getting up and down, and even putting on socks and shoes.

Rate of Depressive Symptoms Is More Than Twice as Common Compared With People Without KOA

Even though knee OA is associated with depression, it has been unclear what components of the OA disease contribute to depression risk, says Rathbun. “Metanalysis evidence indicates the presence of depressive symptoms in this population to be about 20 percent, more than double general population estimates,” he says. Depression in knee OA is associated with decreased quality of life, more health-care costs and use, and an increased mortality rate, he adds.

Do Knee Problems Predispose People to Mood Issues?

“We know that disease progression in patients with knee OA can lead to deteriorating psychosocial health,” said Professor Thomas Dörner, Chairperson of the Abstract Selection Committee for EULAR,” in a EULAR press release. “The results of this study provide valuable insights into the components of OA disease severity, which are related to depression onset.”

What Does Radiographic Disease Mean in Terms of Osteoarthritis?

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Rathbun and his fellow researchers analyzed data for 1,652 patients enrolled in the Osteoarthritis Initiative. Subjects were ages 45 to 79 who had radiographic disease but did not show signs of depression at the beginning of the study. Radiographic disease means that knee OA could be detected through an MRI. After the initial visit the people were followed for three years in annual follow-up visits.

Focusing on How OA Progression Relates to Symptoms of Depression and Vice Versa

The OA disease severity measurement categories were evaluated as a moving average during each follow-up visit and then ranked in quintiles. Joint space width and gait speed categories were inverted so that narrower joint space and slower gait speed corresponded with greater disease severity. This method allowed for greater insight into the relationships between the disease progression and depressive symptoms, as prior studies have examined only how pain and disability (or changes in pain and disability) at one time point are associated with risk or severity of depression at the same or subsequent time points, notes Rathbun.

This study also provides insights that don’t necessarily confirm the intuitive hypothesis, that is, that greater pain would be the best predictor for the likelihood of depression. “Study findings imply that exposure to worsening structural disease severity (and not pain and disability) is the predominant risk factor for depression in this population,” says Rathbun. “Participants with the greatest disability were also at an increased risk, but the magnitude of the association was not as large as the association for structural severity.”

Take Note: Risk for Mental Health Issues Can Increase With Arthritis Disease Progression

These findings could impact the way that physicians treat knee OA, says Rathbun. Newly diagnosed OA patients could be advised that as structural disease progression occurs over time, they are at a greater risk for experiencing depression, he says. “Patient awareness regarding the potential mental health consequences of their chronic physical disease is critical for prevention, and in instances of depression onset, may help mitigate the stigma associated with seeking mental health-care services,” he says.

How Doctors May Use Data to Improve Care for People With KOA

“Health-care providers can use our findings to further identify potential patients who are at the highest likelihood of experiencing depression, for example, persons with a history of severe structural disease rather than simply individuals with symptomatic knee pain,” says Rathbun. “Considering that depression is often under-recognized and undertreated in this population, physician awareness of who is most likely to experience depression is integral to effectively identifying and managing these patients.”

Diagnosing and Treating Depression Is Important, Especially With Chronic Pain

These findings confirm what makes intuitive sense about depression and a disease like OA where they can be chronic pain, says Barbara R. Sommer, MD, associate professor emerita in the department of psychiatry at Stanford University School of Medicine in California. “If someone has depression, treat it,” she says, adding that it will typically lead to better outcomes. “They’ll have more energy and be able to be more active, and ultimately, they will be better able to manage the condition.”

Coexisiting Conditions May Influence Each Other

Ultimately, studies like this one should help guide treatment strategies to improve outcomes. “The association between OA disease severity and depressive symptoms is bidirectional, where each condition simultaneously influences the other as condition-specific symptoms change over time,” says Rathbun. This leads to form a positive feedback loop that worsens the experience of both conditions and decreases the efficacy of treatment strategies that are focused on just one of the diseases, he says.

“A strategy comprising two interventions, with treatments that exhibit cross-condition effects (that affect both OA and depression), could disrupt the positive symptomatic feedback loops that form in these patients and maximize any therapeutic benefits of medical management,” says Rathbun.